The present invention relates generally to the field of hearing aid compatible devices.
Typical speakers from phone handsets may be difficult for hearing aids to pick up, making use of a standard phone with a hearing aid more difficult. To overcome this problem, many hearing aids use a telecoil to amplify voice signals received from a telephone's speaker by coupling to a magnetic field produced by the speaker during use and reproducing the sound produced by the speaker using the magnetically coupled signal. The hearing aid then converts the received signal into an audible (sound) signal and may further reproduce the audible signals at the volume set by the user. Many hearing aids allow a user to switch between a normal listening mode where the hearing aid detects and amplifies sound received by the hearing aid, and a telecoil mode where the hearing aid uses the telecoil to produce the sound provided to the user.
Although wireless phones were previously exempt from being compatible with hearing aids, the Federal Communications Commission (FCC) has modified the previous exemption for wireless phones under the Hearing Aid Compatibility (HAC) Act of 1988 to require that wireless phone manufacturers and wireless phone service providers make digital wireless phones accessible to individuals who use hearing aids. Wireless phones which meet this new requirement are sometimes referred to as HAC-compliant.
Telecoils used in typical land-line telephone headsets produce a magnetic field in the direction of an induction coil of a hearing aid worn by the telephone's user. The telecoil produces the magnetic field to reduce an amount of feedback (e.g., whistle, hum, etc.) generated when an object such as a telephone handset is placed in close proximity to the hearing aid's microphone. The hearing aid's telecoil couples to the magnetic field and uses this magnetic field to provide a desired tone quality.